Predation of Leatherback Turtle Hatchlings During the Crawl to the Water

Abstract

The high probability of being depredated on the crawl to the water may have influenced the evolutionary processes of hatchling sea turtles on the beach. During this time hatchlings must locate water and move as quickly as possible in order to reduce the time spent on the beach. Hatchling leatherback turtles (Dermochelys coriacea) at Playa Grande, Parque Nacional Marino Las Baulas, Costa Rica, spent on average 34 minutes visible on the beach, covered a distance of 46.8 m, and moved at a rate of 3.11 m/min. During the time on the beach, 12% of hatchlings were eaten by predators, 83% reached the water, and 5% were determined as potential mortalities (hatchlings were stuck on debris, vegetation, or upside down). The main predators of hatchling leatherbacks at Playa Grande were ghost crabs (Ocypode occidentalis), great blue herons (Ardea herodias), and yellow-crowned night herons (Nycticorax violaceus) during the night, and crested caracaras (Caracara plancus) during the day. Tracks left by the hatchlings on the sand were straighter as they approached the water. Dispersion (distance between the 2 outermost tracks coming from a nest) was correlated with number of hatchlings crawling. Hatchling leatherback turtles at Playa Grande are threatened by predation by domestic animals. Hatchling mortality due to human-related activities is likely to increase in the future due to increasing pressure from tourism at Parque Nacional Marino Las Baulas.